Alright, let's work through 1644 times 1556 step by step
1644 × 1556 = 1556 × (1644)
+ 1556 × 4 resulting in 6224
+ 1556 × 40 that equals 62240
+ 1556 × 600 which equals 933600
+ 1556 × 1000 that equals 1556000

= 2558064
